London Metropolitan University's"Heliomet SunBloc"European Solar Decathlon house combines novel construction methods with unusual materials. The house is designed so that it can be placed on the rooftops of existing buildings or other disused areas, answering a difficult question about future suburban growth. Allied with a PV-T (PhotoVoltaic-Thermal) array, the design would help supply electricity and hot water not only to its own structure, but to the host building as well.

The primary material consists of relatively low-cost and lightweight EPS foam that allows unique interior and exterior designs to be created. The blocks are pre-cut prior to arrival at the construction site, reducing labour and waste in the process. This London team also allows for hugely innovative designs that can be broken down into pellets after use, adding to the house’s sustainable credentials. The University has been investigating using a foam made from natural sugar, but this is still at a prototype stage. With assistance from local experts, the material has been fully treated to meet stringent fire regulations.

The EPS foam also allows for shelving and furniture to be integrated into the walls. This idea has allowed the team to incorporate a living wall into the house, which can be used by the residents to aid in their food supply or simply to purify the air inside the building while adding to the general aesthetics.

The students were inspired by previous Passivhaus designs and principles and that led them to choose the PV-T system, a combination of a PV array and solar thermal water heating system. This basically works as photovoltaic panels lose their efficiency at higher temperatures, thus the cooling effect from the water helps increase electrical output and the by-product of this is hot water that can then be used in the house.

Further ideas that may be implemented in the design are grey-water tanks in the walls to add weight to their lightweight form, acting as a ballast depending on the location of the building and reducing water usage by recycling water for toilet flushing.

The interiors can be tailored to the requirements of each individual and the chosen design for the Solar Decathlon is intended to provide a comfortable home for a couple that includes ample living space, a fitted kitchen and a large bedroom. The whole house has been designed to be fully constructed in under a fortnight and will be in place for the opening of the Solar Decathlon on 14th September in Casa de Campo, Madrid.